Term | Definition |
Enthalphy change of formation | The enthalpy change when 1 mole of a compound is formed from it's constituent elements under standard conditions with all reactants and products in their standard states |
The bond dissociation enthalpy | The enthalpy change when all the bonds of the same type in 1 mole of gaseous molecules are broken |
Enthalphy change of atomisation of an element | The enthalpy change when 1 mole of gaseous atoms is formed from an element in its standard state |
Enthalphy change of atomisation of a compound | The enthalpy change when 1 mole of a compound in its standard state is converted into gaseous atoms |
The first ionisation enthalpy | The enthalpy change when 1 mole of gaseous 1+ ions is formed from 1 mole of gaseous atoms |
The second ionisation enthalpy | The enthalpy change when 1 mole of gaseous 2+ ions is formed from 1 mole of gaseous 1+ ions |
First electron affinity | The enthalpy change when 1 mole of gaseous 1- ions is made from 1 mole of gaseous atoms |
Second electron affinity | The enthalpy change when 1 mole of gaseous 2- ions is made from 1 mole of gaseous 1- ions |
The enthalpy of hydration | The enthalpy change when 1 mole of aqueous ions is formed from gaseous ions |
The enthalpy change of solution | The enthalpy change when 1 mole of solute is dissolved in sufficient solvent that no further enthalpy change occurs on further dilution. |
Lattice formation enthalpy | The enthalpy change when 1 mole of a solid ionic compound is formed from its gaseous ions under standard conditions |
Lattice dissociation enthalpy | The enthalpy change when 1 mol of a solid ionic compound is completely dissociated inot its gaseous ions under standard conditions |
Enthalpy change | Is the heat energy transferred in a reaction at constant pressure |
Standard conditions | 100kPa 298K 1moldm^3 all substances in their standard states |
Exothermic reaction | give out energy to surroundings so the products have less energy than the reactants. -ve deltaH |
Endothermic reaction | take in energy from surroundings so products have more energy than the reactants. +ve deltaH |
Enthalpy change of combustion | The enthalpy change when 1 mole of a substance is completely burned with oxygen under standard conditions with all reactants and products in their standard states |
Hess's Law | The enthalpy change is the same independent of the route taken. |